Many conventional residential heating and cooling systems include a disposable filter. These filters typically include a frame, a filter material formed of glass fibers or similar material, and a mesh screen or the like that supports the filter material. After a period of use, these filters become dirty or clogged and must be replaced. This is accomplished by replacing the entire filter assembly with a new filter and discarding the old one. Depending on the use of the filter, replacement may be required several times a year. Because the frame and screen are discarded with the assembly even though it is only the filter material that is no longer functional, there is unnecessary waste and cost associated with such filters. In addition, because these filters are rather bulky, they are often purchased as they are needed rather than keeping a large supply on hand. Because purchasing a new filter is not always convenient, replacement can be delayed resulting in reduced efficiency of the system.
Filter assemblies with frames and removable filter elements are known in the prior art. U.S. Pat. No. 3,280,984 (Sexton et al.), for example, discloses a filter assembly comprising a support frame including upstream and downstream grid retaining panels and a flat pad of filter medium disposed in the frame.
U.S. Pat. No. 3,774,377 (Bishop) discloses a filter assembly with a replaceable filter element including a frame, a disposable and replaceable filter medium, and means for retaining the filter medium in a fixed position in the frame.
U.S. Pat. No. 3,789,589 (Delany et al.) discloses a filter assembly including a casing and a drawer arranged in the casing that contains pleated filter media. The drawer includes a plurality of comb-like assemblies having pointed fingers that are disposed in the pockets of the pleated filter media to prevent the filter from collapsing. The filter includes strips extending across each end portion of the downstream side of the filter so the side edges of the downstream folds will be equally spaced.
U.S. Pat. No. 4,042,358 (Frohmader) discloses an air filter formed into an accordion-shaped body having reverse folds forming pockets. The filter includes a string-like pleat spacing member that passes through a series of openings in the pleat walls. The spacing member is intended to equally space the pleats when the filter is in its expanded condition.
U.S. Pat. No. 5,840,094 (Osendorf et al.) discloses a filter assembly including first and second frame members, a filter element, and separate comb-like spacers for retaining the filter pleats in an open spaced manner.
U.S. Pat. No. 6,033,453 (Weddell, III) discloses a reusable frame support rack for supporting and retaining an outstretched, replaceable pleated media filter core. The frame includes a pair of longitudinal angles extending between a pair of transverse angles which carry a flat expanded metal support or reinforcement system.
There remains a need, however, for a filter assembly including a reusable frame and a collapsible, replaceable, pleated filter element that is easy to assemble and use.
It would therefore be desirable to provide a filter assembly including a reusable frame and a collapsible replaceable pleated filter element that can be collapsed for compact shipping, storage, and disposal but can be quickly and easily expanded with uniform spacing and installed in the frame.